JP2011223820A - Disk drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin and stable disk drive device.SOLUTION: The disk drive device includes: a base member; a hub on which a recording disk is placed; a bearing unit arranged on the base member, for rotatably supporting the hub; and a spindle drive unit for rotationally driving the hub. In the disk drive device, the spindle drive unit includes a stator core having salient poles, a coil wound around each of the salient poles, and a magnet facing the salient poles and having a plurality of magnetic poles arranged in a circumferential direction, and the hub includes an outer cylindrical portion formed of a magnetic material and engaged with an inner periphery of the recording disk, and an inner cylindrical portion fixing an outer periphery of the magnet. The number of magnetic poles is an even number in a range of 10 to 16, and the number of salient poles is a multiple of 3 in a range of 12 to 24.

Description

  The present invention relates to a disk drive device including a hub on which a recording disk is placed.

  2. Description of the Related Art In recent years, disk drive devices such as HDDs have been improved in bearing rigidity by including a fluid dynamic pressure bearing unit. A disk drive device including this fluid dynamic pressure bearing unit may be mounted on a small portable device. Mobile devices are required to be thinner and lighter, and disk drives mounted on mobile devices are also required to be thinner and lighter.

  For example, Patent Literature 1 includes a disk drive in which a fluid dynamic pressure bearing unit is provided, and the first radial dynamic pressure groove is formed in a narrower axial width than the second radial dynamic pressure groove in the axial direction. An apparatus is disclosed.

JP 2007-198555 A

  In order to reduce the thickness of the disk drive device, it is necessary to make the spindle drive unit and the fluid dynamic bearing unit thin. Here, if the spindle driving unit is made thinner, the torque may be reduced, and the rotation may become unstable. Further, when the fluid dynamic pressure bearing unit is made thinner, the rigidity of the fluid dynamic pressure bearing unit may be lowered, and rotation may become unstable. If the rotation becomes unstable in this way, there is a problem that can be a hindrance to normal magnetic data read and write operations.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a disk drive device that stabilizes the rotation of the recording disk while making the disk drive device thinner.

  In order to solve the above problems, a disk drive device according to an aspect of the present invention includes a base member, a hub on which a recording disk is placed, and a bearing that is disposed on the base member and rotatably supports the hub. A unit, and a spindle drive unit that rotationally drives the hub. The spindle drive unit includes a stator core having salient poles, a coil wound around the salient poles, and a magnet having a plurality of magnetic poles in the circumferential direction facing the salient poles. The hub is formed of a magnetic material, and has an outer cylinder part that engages with the inner periphery of the recording disk, and an inner cylinder part to which the outer periphery of the magnet is fixed. The number of magnetic poles is an even number in the range of 10 to 16, and the number of salient poles is a multiple of 3 in the range of 12 to 24.

  According to this aspect, the total number of turns of the coil can be increased by increasing the number of salient poles to 12 or more. As a result, even in a thin disk drive device, the total number of turns of the coil can be sufficiently secured, a reduction in torque can be reduced, and the rotation of the recording disk can be stabilized.

  According to the present invention, the rotation of the recording disk can be stabilized while making the disk drive device thinner.

(A) And (b) is a figure which shows the disk drive device which concerns on embodiment. 1 is a cross-sectional view of a part of a disk drive device according to an embodiment. It is sectional drawing of the hub which concerns on embodiment. It is a partial cross-sectional view of a disk drive device according to a comparative technique. (A)-(c) is a figure which shows the shaping | molding method of the coil which concerns on embodiment.

In the following, the same or equivalent components and members shown in the drawings are denoted by the same reference numerals, and repeated description thereof will be omitted as appropriate. In addition, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. In the following description, for the sake of convenience, the lower part shown in the drawings is expressed as lower and the upper part is expressed as upper.
As an example, the disk drive device 100 is assumed to rotate by driving a so-called 2.5-inch hard disk made of glass having an outer diameter of about 65 mm, an inner diameter of about 20 mm, and a thickness of about 0.75 mm. explain.

  1A and 1B show a disk drive device 100 according to an embodiment. FIG. 1A is a top view of the disk drive device 100, and FIG. 1B is a lateral view of the disk drive device 100. FIG. 1A shows a state in which the top cover 2 is removed. FIG. 2 is a cross-sectional view of a part of the disk drive device 100 according to the embodiment. FIG. 3 is a cross-sectional view of the hub 4 according to the embodiment. 2 and 3 are cross-sectional views taken along the line AB in FIG.

  The disk drive device 100 is disposed on the base member 3 and the chassis 10 having the base member 3 and the circumferential ring wall 15, the hub 4 on which the donut-shaped recording disk 1 is placed, and the hub 4 is rotatable. , A spindle drive unit 6 that rotates the hub 4, a head drive unit 17, a top cover 2, and a screw 9. In addition, the disk drive device 100 includes a fixed body portion 7 formed of a fixed member that does not rotate and a rotating body portion 8 formed of a rotating member. The fixed body portion 7 and the rotating body portion 8 include a hub. A bearing unit 5 that rotatably supports 4 and a spindle drive unit 6 that rotationally drives the hub 4 are included.

  The chassis 10 includes a base member 3 that is a planar region of a recessed portion and a peripheral annular wall portion 15 formed in a wall shape on the outer periphery of the base member 3. The base member 3 has a housing 13 and a bearing hole 3A into which the sleeve 14 and the shaft 16 are inserted. The outer peripheral surface of the circumferential ring wall 15 is formed in a rectangular shape. The inner peripheral surface of the peripheral annular wall portion 15 is formed by connecting an annular portion 15A surrounding the recording disk 1 and a rectangular portion 15B surrounding an area where the head drive unit 17 is placed. The circumferential ring wall portion 15 functions as a support member of the disk drive device 100 that supports the shaft 16 in the direction of the rotation axis. On the other hand, the base member 3 functions as a support member of the disk drive device 100 that supports the shaft 16 in a direction perpendicular to the rotation axis direction of the shaft 16.

  The top cover 2 shown in FIG. 1B is provided at the upper end of the circumferential ring wall 15 and is fixed by screwing the screw 9 into a screw hole 15C formed on the upper end surface side of the circumferential ring wall 15. Is done. A clean air space is formed by sealing with the chassis 10 and the top cover 2 covering the space of the recessed portion of the chassis 10. The clean air space is filled with clean air from which particles have been removed. In the clean air space, a recording disk 1, which is a magnetic recording medium, a rotating body unit 8, and a head drive unit 17 are arranged.

  The thickness of the disk drive device 100 is defined as a dimension along the direction of the rotation axis of the recording disk 1 from the upper end surface of the top cover 2 to the lower end surface of the base member 3. The disk drive device 100 mounted on a portable device has problems of further reduction in thickness and weight. In response to this problem, in the disk drive device 100 of this embodiment, the inner diameter of the recording disk 1 is 20 mm, and the axial thickness of the disk drive device 100 is 7 mm, which is 7.5 mm or less. As a result, the portable device can be configured to be thin and lightweight. It can also contribute to resource saving.

  The bearing unit 5 is disposed on the base member 3 and includes a shaft 16, a sleeve 14, a housing 13, an overhang member 19, and a hanging portion 20. The bearing unit 5 includes a radial dynamic pressure groove 22, a thrust dynamic pressure groove 23, and a capillary seal portion 24.

  The shaft 16 functions as a rotating shaft, and the upper end portion of the shaft 16 is fixed to a shaft hole 4 </ b> M formed at the center of the hub 4. The shaft 16 is inserted into the sleeve 14. The substantially cylindrical sleeve 14 is inserted into the housing 13, and a part of the outer peripheral surface of the sleeve 14 is fixed to the inner peripheral surface of the housing 13 by bonding or the like. An overhanging member 19 that projects outward in the radial direction is fixed to the opening end surface 14A on the upper side of the sleeve 14. The overhang member 19 cooperates with the hanging portion 20 to limit the movement of the hub 4 in the axial direction. Further, the protruding member 19 and the hanging part 20 prevent the rotating body part 8 from coming off.

  The housing 13 is formed in a bottomed cup shape, and a part of the outer peripheral surface of the housing 13 is fixed to the bearing hole 3 </ b> A at the substantially central portion of the base member 3. A bottom portion is formed at the lower end portion of the housing 13, and the bottom portion is sealed so that the lubricant does not leak outside.

  The radial dynamic pressure groove 22 and the thrust dynamic pressure groove 23 function as bearings that rotatably support the hub 4. Two herringbone-shaped radial dynamic pressure grooves 22 are formed on at least one of the inner peripheral surface of the sleeve 14 and the outer peripheral surface of the shaft 16 so as to be vertically separated from each other. Further, a herringbone-shaped or spiral-shaped thrust dynamic pressure groove 23 is formed on the surface of the hanging portion 20 facing the opening end surface of the housing 13 and the upper surface of the hanging portion 20 facing the lower surface of the overhanging member 19. The The thrust dynamic pressure groove 23 may be formed on at least one of the opening end surface 14A of the sleeve 14 and the lower end surface 4F of the hub 4 facing the opening end surface 14A.

  When the shaft 16 rotates, the radial dynamic pressure groove 22 generates radial dynamic pressure in the lubricant, and the rotating body portion 8 is supported in the radial direction. When the hanging part 20 rotates, the thrust dynamic pressure groove 23 generates a thrust dynamic pressure in the lubricant, and the rotating body part 8 is supported in the thrust direction.

  The capillary seal portion 24 is formed by the inner circumferential surface of the cylindrical portion of the hanging portion 20 and the outer circumferential surface of the housing 13, and the gap between the inner circumferential surface of the hanging portion 20 and the outer circumferential surface of the housing 13 faces the lower open end. It is formed to gradually expand. Lubricant such as oil is injected into the space formed by the radial dynamic pressure groove 22 and the surface facing it, the thrust dynamic pressure groove 23 and the surface facing it, and the capillary seal portion 24. The boundary surface (liquid level) at which the lubricant comes into contact with the outside air is set at a midway position in the capillary seal portion 24. The capillary seal portion 24 can prevent the lubricant from leaking out by capillary action.

  The spindle drive unit 6 includes a stator core 11 fixed to the base member 3, a three-phase coil 12 wound around the salient poles of the stator core 11, and a substantially cylindrical magnet 21 fixed to the inner cylinder portion 4 </ b> D of the hub 4. And including.

The stator core 11 has an annular portion and a plurality of salient poles extending in the radial direction therefrom. The stator core 11 is formed by laminating a plurality of magnetic plate materials such as silicon steel plates, and then subjecting the surface to insulation coding by electrodeposition coating or powder coating. As an example, the stator core 11 may have a shape dimension of 1 mm by laminating five silicon steel plates having an inner diameter of the annular portion of 9 mm, a diameter of a circumscribed circle of the salient pole of 18 mm, and a thickness of 0.2 mm.
The magnet 21 is formed of, for example, an Nd—Fe—B (neodymium-iron-boron) rare earth material, and the surface thereof is subjected to rust prevention treatment by electrodeposition coating, spray coating, or the like. The magnet 21 has a plurality of driving magnetic poles along the circumferential direction of the inner peripheral portion of the magnet 21. The magnet 21 faces the protruding end of the salient pole. For example, the magnet 21 may have a substantially ring shape with an inner diameter of 18.4 mm, an outer diameter of 20.4 mm, and an axial thickness of 2 mm.

  In the coil 12, the wire 25 is wound around the salient pole of the stator core 11 from the lower side a predetermined number of times, and then the wire 25 is continuously wound around the salient pole of the adjacent stator core 11 from the upper side. For example, the axial dimension of the coil 12 wound around the salient pole may be 0.6 mm. In this way, after continuously winding a predetermined number of times on the salient poles of the stator core 11, the wire 25 at the end of winding is pulled out below the salient poles of the stator core 11. Further, the wire 25 at the end of winding is pulled out to the opposite side of the base member 3 through the wire hole 3B provided in the base member 3 and is electrically connected to the wiring member 26 disposed on the lower surface of the base member 3. The winding end portion of the drawn wire 25 is fixed with an adhesive so that it cannot be unwound. Such fixing prevents the wire 25 from resonating and vibrating with a large amplitude during ultrasonic cleaning. When a three-phase substantially sinusoidal current is passed through the wiring member 26 by a predetermined drive circuit, the coil 12 generates a rotating magnetic field at the salient pole of the stator core 11. A rotational driving force is generated by the interaction between the driving magnetic pole of the magnet 21 and the rotating magnetic field, and the rotating body 8 rotates. That is, the spindle drive unit 6 drives the rotating body unit 8 to rotate.

Here, the spindle drive unit 6 will be described in more detail.
In order to reduce the axial thickness of the disk drive device 100, there is a method of reducing the axial dimension from the upper end of the hub 4 to the lower end of the base member 3 (hereinafter referred to as the axial dimension X). For example, the axial dimension X can be 6 mm or less. As a result, even when the top cover 2 and the gap between the top cover 2 and the hub 4 are added, the axial thickness of the disk drive device 100 can be configured to be 7 mm or less. The axial dimension X can be 5.5 mm or less. As a result, the axial thickness of the disk drive device 100 can be more easily configured to be 7 mm or less.

  In order to make the axial dimension X thin, the axial dimension (hereinafter referred to as the axial dimension Y) of the portion where the hub 4, the base member 3, the stator core 11 and the coil 12 of the disk drive device 100 overlap in the axial direction. Is generally thin. For example, the axial dimension Y can be set to 5.3 mm or less. As a result, the axial dimension X can be set to 6 mm or less even in consideration of the space in which the clamper 29 for fixing the recording disk 1 to the hub 4 is disposed. The axial dimension Y can be 4.8 mm or less. As a result, the axial dimension X can be easily configured to 5.5 mm or less.

  However, if the hub 4 or the base member 3 is thinned to reduce the axial dimension Y, the rigidity of the disk drive device 100 may be reduced. When the rigidity of the disk drive device 100 decreases, the recording disk 1 vibrates and the data recording / reproducing operation becomes unstable even under a slight impact. For this reason, the axial dimension (hereinafter referred to as the axial dimension Z) of the surface of the coil 12 facing the hub 4 and the surface facing the base member may be 3 mm or less. By setting the axial dimension Z to 3 mm or less, even when the axial dimension Y is set to 5.3 mm or less, it is preferable in terms of suppressing a decrease in rigidity of the hub 4 and the base member 3. When the axial dimension Z is reduced, the salient poles of the stator core 11 are also reduced and the strength is reduced, and deformation may occur when the coil 12 is wound. When the outside diameter of the salient pole is 15 to 25 mm and the axial dimension Z is 2 mm or more, it is confirmed by the inventors' experiment that the deformation of the salient pole during the winding operation of the coil 12 is within an allowable range. Has been.

  In order to reduce the axial dimension Z, the coil 12 is generally made thinner. When the coil 12 is thinned, the number of turns of the coil 12 that can be wound around the salient pole of the stator core 11 is reduced. If the number of turns of the coil 12 is small, the torque of the spindle drive unit 6 is reduced, so that the rotation becomes unstable. If the rotation becomes unstable, it can be a hindrance to normal magnetic data read and write operations.

  Correspondingly, in the disk drive device 100 of the present embodiment, the number of salient poles of the stator core 11 is set to 12 or more. The number of turns of the coil 12 increases according to the number of salient poles of the stator core 11. By increasing the number of salient poles of the stator core 11 to 12 or more, even if the coil 12 is made thinner, a reduction in torque of the spindle drive unit 6 due to the number of turns of the coil 12 can be suppressed and good rotation can be obtained. . The number of salient poles of the stator core 11 may be a multiple of three so that the spindle drive unit 6 is driven in three phases. This is preferable in that a smooth driving torque can be obtained. When the number of salient poles of the stator core 11 is increased, the salient poles become thin, so that they easily deform, requiring careful processing and taking time for assembly. By setting the number of salient poles of the stator core 11 to 24 or less, for example, even when the diameter of the circumscribed circle of the salient poles of the stator core 11 is 25 mm or less, this is preferable.

  It has been found by experiments of the present inventors that when the number of magnetic poles for driving the magnet 21 is small, vibration due to torque pulsation of the spindle drive unit 6 is large. If the vibration of the spindle drive unit 6 is large, the magnetic head of the head drive unit 17 may vibrate and may interfere with normal magnetic data read and write operations. Correspondingly, the number of drive magnetic poles of the magnet 21 is configured to be 10 or more in the disk drive device 100 of the present embodiment. By increasing the number of drive magnetic poles of the magnet 21 to 10 or more, vibration of the spindle drive unit 6 can be suppressed. When the number of driving magnetic poles of the magnet 21 is increased, the interval between the adjacent magnetic poles becomes narrow, so that it is difficult to magnetize with sufficient strength. If the drive magnetic poles of the magnet 21 are not sufficiently magnetized, the torque of the spindle drive unit 6 is reduced and the rotation becomes unstable. If the rotation becomes unstable, it can be a hindrance to normal magnetic data read and write operations. By setting the number of driving magnetic poles of the magnet 21 to 16 or less, it is preferable because the magnet 21 can be magnetized with sufficient strength even when the inner diameter of the magnet 21 is 25 mm or less, for example.

  For example, when the diameter of the circumscribed circle of the salient pole of the stator core 11 is 15 to 25 mm, the inner diameter of the magnet 21 is 15 to 25 mm, and the axial dimension Y is 4.3 to 5.3 mm, the driving magnetic pole of the magnet 21 The inventors have confirmed through experiments that the number can be 10 and the number of salient poles of the stator core 11 can be 15. In addition, the inventors have confirmed through experiments that such a configuration can suppress a decrease in the torque of the spindle drive unit 6 to ensure good rotation and reduce vibration. Further, the inventors have confirmed through experiments that the stator core 11 can be easily processed.

  For example, when the diameter of the circumscribed circle of the salient pole of the stator core 11 is 15 to 25 mm, the inner diameter of the magnet 21 is 15 to 25 mm, and the axial dimension Y is 4.3 to 5.3 mm, for driving the magnet 21 The inventors have confirmed through experiments that the number of magnetic poles can be 12 and the number of salient poles of the stator core 11 can be 18. In addition, the inventors have confirmed through experiments that such a configuration can further suppress a decrease in the torque of the spindle drive unit 6 to ensure good rotation and reduce vibration. Further, the inventors have confirmed through experiments that the stator core 11 can be easily processed.

  For example, when the diameter of the circumscribed circle of the salient pole of the stator core 11 is 15 to 25 mm, the inner diameter of the magnet 21 is 15 to 25 mm, and the axial dimension Y is 4.3 to 5.3 mm, for driving the magnet 21 The inventors have confirmed through experiments that the number of magnetic poles can be 14 and the number of salient poles of the stator core 11 can be 21. In addition, the inventors have confirmed through experiments that such a configuration can suppress a decrease in the torque of the spindle drive unit 6 to ensure good rotation and reduce vibration. Further, the inventors have confirmed through experiments that the stator core 11 can be easily processed.

  For example, when the diameter of the circumscribed circle of the salient pole of the stator core 11 is 15 to 25 mm, the inner diameter of the magnet 21 is 15 to 25 mm, and the axial dimension Y is 4.3 to 5.3 mm, for driving the magnet 21 The inventors have confirmed through experiments that the number of magnetic poles can be 16 and the number of salient poles of the stator core 11 can be 24. In addition, the inventors have confirmed through experiments that such a configuration can suppress a decrease in the torque of the spindle drive unit 6 to ensure good rotation and reduce vibration. Further, the inventors have confirmed through experiments that the stator core 11 can be easily processed.

  For example, when the diameter of the circumscribed circle of the salient pole of the stator core 11 is 15 to 25 mm, the inner diameter of the magnet 21 is 15 to 25 mm, and the axial dimension Y is 4.3 to 5.3 mm, for driving the magnet 21 The inventors have confirmed through experiments that the number of magnetic poles can be 16 and the number of salient poles of the stator core 11 can be 12. In addition, the inventors have confirmed through experiments that such a configuration can suppress a decrease in the torque of the spindle drive unit 6 to ensure good rotation and further reduce vibration. Further, the inventors have confirmed through experiments that the stator core 11 can be easily processed.

  The fixed body portion 7 includes a chassis 10 having a substantially concave cross section, a stator core 11, a coil 12, a housing 13, and a sleeve 14. The rotating body 8 includes a substantially saucer-shaped hub 4 on which the recording disk 1 is placed, a shaft 16, and a magnet 21.

  Here, the hub 4 will be specifically described with reference to FIG. The hub 4 is formed of a magnetic material such as SUS430F having soft magnetism. It is preferable that the entire hub 4 is made of a magnetic material because a magnetic shielding effect is produced. The hub 4 is formed by pressing a steel plate by pressing or cutting to form a predetermined shape that is substantially a saucer. For example, a stainless steel with a trade name of DHS1 manufactured by Daido Steel Co., Ltd. is preferable in that it has less outgas and is easy to process. Similarly, stainless steel having a trade name of DHS2 is more preferable in terms of further excellent corrosion resistance.

  A shaft hole 4M is formed at the center of the hub 4, and an annular central portion 4I is formed around the shaft hole 4M. The axial dimension of the shaft hole 4M is formed larger than the axial dimension of the central portion 4I facing the upper end surface of the sleeve 14, and a part of the outer peripheral surface of the shaft hole 4M projects downward. Thereby, the joint surface of the hub 4 and the shaft 16 when the thickness is reduced is secured.

  Two annular steps are formed on the upper end surface 4A of the hub 4, and the central portion 4I is positioned at the top. A recess 4J that is recessed one step below the central portion 4I is formed in an annular shape on the upper end surface 4A. For example, the inner diameter of the recess 4J may be 8 mm. It is preferable in terms of easy processing. A clamper 29 is disposed on the upper surface of the recess 4J, and a center hole of the clamper 29 is fitted into an annular step between the center 4I and the recess 4J. For example, the axial dimension of the annular step between the central portion 4I and the recess 4J may be 0.8 mm to 0.7 mm. This is preferable in that the protrusion of the clamper 29 can be suppressed. A clamper locking portion for locking the clamper 29 is formed on the upper surface of the recess 4J. Specifically, a plurality of screw holes 4K are provided on the upper surface of the recess 4J at circumferentially spaced positions to constitute a clamper locking portion. The clamper 29 is locked by screwing the screw 30 into the screw hole 4K.

The annular outer cylinder portion 4B is formed as a step that is recessed from the outer peripheral end of the recess 4J, and an annular extension portion 4C that extends radially outward from the outer peripheral lower end of the outer cylinder portion 4B is formed. The inner periphery of the central hole of the recording disk 1 is engaged with the outer cylinder portion 4B of the hub 4 and placed on the upper surface of the annular extending portion 4C. For example, the diameter of the outer cylinder 4B may be 20 mm, the axial dimension of the step between the upper surface of the annular extension 4C and the recess 4J may be 0.7 to 0.8 mm, and the outer diameter of the annular extension 4C may be 24 mm. A so-called 2.5 inch recording disk 1 can be engaged with high accuracy.
The annular extending portion 4C hangs toward the base member 3, and the outer periphery of the magnet 21 is fixed to the inner cylinder portion 4D. The annular extending portion 4 </ b> C located in the radially outer region of the outer periphery of the magnet 21 functions as a back yoke of the magnet 21. For example, the axial dimension of the annular extension 4C may be 2.5 to 3 mm. This is preferable in that the leakage magnetic flux can be suppressed.

  On the lower surface of the hub 4, an annular protrusion 4 </ b> E protruding in the direction of the base member 3 is formed between the housing 13 and the stator core 11. An annular hanging portion 20 is fixed to the inner peripheral surface of the annular protrusion 4E of the hub 4 by adhesion.

  The lower end surface 4F of the hub 4 facing the open end surface 14A of the sleeve 14 is located on the back surface of the central portion 4I. A portion 4H facing the coil 12 of the hub 4 is located on the back surface of the recess 4J.

  Here, problems recognized by the present inventor will be described based on the configuration related to the comparison technique shown in FIG. FIG. 4 is a cross-sectional view of a part of the disk drive device 200 according to the comparative technique. When the disk drive device 200 according to the comparative technique is made thinner, the spindle drive unit 52 such as the stator core 50 becomes thinner accordingly. When the spindle drive unit 52 becomes thinner, the torque becomes lower and the rotation becomes unstable. When the rotation becomes unstable, there is a problem that can be a hindrance to normal read / write operations of magnetic data.

  There is also a method of using a magnet 54 having a larger diameter in order to recover the reduced torque. However, in the configuration in which the recording disk 1 is located in a region on the extension of the outer periphery of the magnet 54, the back yoke portion 58 of the hub 56 sandwiched between the inner periphery of the recording disk 1 and the outer periphery of the magnet 54 is It becomes thin according to the diameter of 54. The back yoke portion 58 is a part of a magnetic circuit through which the magnetic flux emitted from the outer periphery of the magnet 54 passes, and becomes magnetically saturated when it becomes thin. When the magnetic saturation occurs, the magnetic flux does not increase even if the magnetic field is strengthened, and the increase of the magnetic flux that contributes to the torque becomes slight, and the torque cannot be increased. On the other hand, the magnetic flux leaking to the recording disk 1 side greatly increases. Therefore, in the configuration in which the recording disk 1 is positioned on the extension of the outer periphery of the magnet 54, there is a possibility that normal magnetic data read and write operations may be obstructed by the leakage magnetic flux, and the disk drive device 200 is made thinner. It was an obstruction factor. Further, even if the back yoke portion is made thicker in the comparative technique, the magnet 54 must be made smaller by that amount, and an increase in torque cannot be expected.

  Returning to FIG. In order to cope with this problem, the recording disk 1 according to the embodiment is disposed at an upper position separated from the magnet 21 in the axial direction, away from a region on the radial extension of the outer periphery of the magnet 21. With this configuration, the magnetic flux leaking to the recording disk 1 side can be reduced. The diameter of the inner cylinder portion 4D of the hub 4 is configured to be larger than the diameter of the outer cylinder portion 4B of the hub 4. As a result, the outer periphery of the magnet 21 can be configured to be large, the amount of magnetic flux of the driving magnetic pole is increased, the torque is increased, and this is suitable for the thin disk drive device 100. Further, by arranging the recording disk 1 at a position on the upper side in the axial direction while avoiding the region on the radially extending outer periphery of the magnet 21, the back yoke of the hub 4 can be configured to be sufficiently thick in the radial direction. As a result, even if the magnet 21 having a larger energy product is employed, the influence of the leakage magnetic flux can be reduced and the torque can be increased.

  For example, if the hub 4 is made of a magnetic material and the axial distance between the upper surface of the annular extension 4C on which the recording disk 1 is placed and the upper surface of the magnet 54 is 1 mm or less, the disk drive device 100 can be made thinner. Is preferable. In addition, it is preferable that the axial distance between the disk mounting surface 4c and the magnet 54 be 0.5 mm or more in terms of suppressing magnetic flux leaking to the recording disk 1 side. Further, for example, the axial distance between the upper surface of the annular extending portion 4C and the upper surface of the magnet 54 can be 0.76 mm. This is advantageous in that the disk drive device 100 can be made thin and leakage flux can be suppressed.

  Further, the diameter of the circle connecting the protruding ends of the stator core 11 may be 80% or more of the diameter of the outer cylinder portion 4B of the hub 4. For example, the diameter of the circumscribed circle of the salient poles of the stator core 11 can be 22 mm, and the diameter of the outer cylinder portion 4B can be 20 mm. By making the stator core 11 large in this way, more coils 12 can be wound, and an increase in torque can be expected. When the number of turns of the coil 12 is constant, the coil 12 can be made thinner by that amount. This is advantageous in that the disk drive device 100 can be made thinner. If the diameter of the circle connecting the protruding ends of the stator core 11 exceeds 140% of the diameter of the outer cylindrical portion 4B, the leakage flux of the magnet 21 acts on the recording disk 1 and obstructs normal magnetic data read and write operations. sell. Therefore, the diameter of the circle connecting the protruding ends of the stator core 11 is preferably in the range of 80% to 140% of the diameter of the outer cylindrical portion 4B.

The base member 3 has a wire hole 3B through which the wire 25 forming the coil 12 is inserted. The lead wire of the wire 25 forming the coil 12 is led out to the back surface 3C on the upper surface where the bearing unit 5 of the base member 3 is disposed through the wire hole 3B.
Here, in the comparison technique of FIG. 4, the lead wire of the wire is connected 68 to the wiring member 66 by soldering at a position directly below the coil 62. The thickness of the wiring member 66 and the height of the connecting portion 68 at a position directly below the coil 62 become an obstacle to making the spindle drive unit 52 thinner.

  Returning to FIG. Corresponding to this problem, the lead wire of the wire 25 is led out to the back surface 3C of the upper surface where the bearing unit 5 of the base member 3 is disposed through the wire hole 3B, and is wired at a position radially outside the outer diameter of the magnet 21. It is electrically connected to the member 26. Thereby, the spindle drive unit 6 can be made thinner by the height of the connecting portion 26A of the lead wire and the wiring member 26. The base member 3 in the region radially outside the magnet 21 can be formed thin because fewer members are disposed on the base member 3 than the region in which the spindle drive unit 6 is disposed. And the connection part 26A can be provided in the area | region of the base member 3 which became thin.

  Further, the base member 3 may be made of a metal such as aluminum. In this case, the wire 25 drawn out to the lower surface 3C of the base member 3 may come into direct contact with the base member 3 and be electrically short-circuited. Corresponding to this problem, a groove 3D for leading a wire from the wire hole 3B to the wiring member 26 is provided on the back surface 3C of the surface on which the bearing unit 5 of the base member 3 is disposed. This groove 3D is insulated. As a result, the problem that the wire 25 is electrically short-circuited with the base member 3 is reduced. Further, by combining the position of the connecting portion 26A described above with the configuration in which the position of the magnet 21 is radially outside, the amount based on the thickness of the wiring member 66 and the height of the connecting portion 68 in the comparative technique shown in FIG. The spindle drive unit 6 can be thinned. The insulation treatment may be, for example, cationic electrodeposition coating (hereinafter referred to as “ED coating”) on the base member 3 formed by die casting aluminum, which is preferable in that there are few pinholes.

  Next, when the disk drive device 100 is made thinner, the coil 12 wound around the salient pole of the stator core 11 and the lower surface of the hub 4 are very close to each other. In this case, the possibility that the coil 12 contacts the rotating hub 4 is increased. When the coil 12 contacts the hub 4, there is a problem that an electrical short circuit occurs. Corresponding to this problem, the surface of the coil 12 facing the hub 4 and the surface facing the base member 3 are leveled.

  5A to 5C show a method for forming the coil 12 according to the embodiment. Fig.5 (a) shows the coil 12 before shaping | molding, FIG.5 (b) shows the coil 12 at the time of a press, and FIG.5 (c) shows the coil 12 after a press. As shown in this figure, the coil 12 is formed by winding the wire 25 around the salient pole of the stator core 11 and then pressing between the first pressing mold 40 and the second pressing mold 42. The pressing surfaces of the first pressing mold 40 and the second pressing mold 42 are flat. By pressing the coil 12 to form it flat, the axial dimension of the coil 12 can be stabilized, and the possibility that the coil 12 contacts the rotating hub 4 can be reduced. The axial dimension of the coil 12 can be reduced. Can be made thinner.

Further, the flatness of the wire 25 forming the smoothed coil 12 may be 90% or less in response to the problem of the coil 12 contacting the rotating hub 4. The flatness of the wire 25 is a percentage of the axial dimension b with respect to the radial dimension a of the cross section of the single wire 25, and the portion of the coil 25 having the lowest flatness. Define in. The formula is shown below.
Flatness of wire 25 = (b / a) × 100
When the coil 12 is press-molded so as to limit the axial dimension of the coil 12, the portion where the flatness of the wire 25 is the lowest is the portion that is thickest in the axial direction. As a result, the possibility that the coil 12 contacts the rotating hub 4 is further reduced.

  Further, the surface of the hub 4 facing the coil 12 may be insulated in response to the problem that the coil 12 contacts the rotating hub 4. As a result, the possibility of causing an electrical short and leading to functional failure is reduced. The insulation process may be performed by a film sticking process in which an adhesive member is interposed on the surface of the hub 4 facing the coil 12 to attach a resin film. For example, a PET (Polyethyleneterephthalate) annular film 27 may be attached to the surface of the hub 4 facing the coil 12 with a double-sided tape. This method is preferable in that the operation is easy.

  Further, there is a problem that the coil 12 contacts the base member 3 to cause an electrical short circuit. In response to this problem, the surface of the base member 3 facing the coil 12 may be insulated. As a result, the possibility that the coil 12 contacts the base member 3 to cause an electrical short is reduced. Insulation treatment is preferable in that, for example, an aluminum die-cast base member 3 may be ED coated, and there are few pinholes. Alternatively, a PET annular film 28 may be attached to the surface of the base member 3 facing the coil 12 with a double-sided tape. This method is preferable in that the work is easy.

  Next, when the disk drive device 100 is thinned, if the axial thickness dimension of the portion 4H facing the coil 12 of the hub 4 is shortened, the rigidity is lowered and the resonance frequency is lowered. From the study of the present inventor, it has been found that the main factors that determine the resonance frequency of the disk drive device 100 are the rigidity of the bearing and the rigidity of the hub 4.

  When the resonance frequency is lowered, large vibrations may occur due to resonance with fluctuations in driving torque. Such vibration has the problem that it can be a hindrance to normal magnetic data read and write operations. In response to this problem, the axial width of the hub 4 facing the coil 12 may be thicker than the axial width of the base member 3 facing the coil 12. This shows the relative relationship between the dimensions of the base member 3 and the hub 4 in the axial direction in the region where the spindle drive unit 6 is disposed when the disk drive device 100 is thinned. For example, the axial width of the hub 4 facing the coil 12 can be 1 to 1.4 mm, and the axial width of the base member 3 facing the coil 12 can be 0.6 to 0.9 mm. This is preferable in that the problems caused by the decrease in rigidity of the hub 4 are reduced. For example, the axial width of the hub 4 facing the coil 12 can be 1.2 mm, and the axial width of the base member 3 facing the coil 12 can be 0.7 mm. This is advantageous in that the problems caused by the decrease in the rigidity of the hub 4 are further reduced.

  Next, in the disk drive device 200 according to the comparative technique shown in FIG. 4, the center portion of the clamper 70 is fixed to the center of the shaft 74 by a screw 72. For this reason, the axial dimension of the central portion of the hub 56 is made thinner by the amount of the clamper 70 and the screw 72. When the axial dimension of the central portion of the hub 56 is reduced, the resonance frequency is lowered, and a large vibration may occur due to resonance with fluctuations in the drive torque.

  Returning to FIG. 2 and FIG. In response to this problem, in the disk drive device 100 according to the embodiment, the clamper 29 is disposed on the upper surface of the recess 4J of the hub 4, and the center hole of the clamper 29 is fitted into the annular step between the center portion 4I and the recess 4J. Combined. A clamper locking portion for locking the clamper 29 is formed on the upper surface of the recess 4J. Specifically, a plurality of screw holes 4K are provided on the upper surface of the recess 4J at circumferentially spaced positions to constitute a clamper locking portion. The clamper 29 is locked by screwing the screw 30 into the screw hole 4K. As a result, the problem caused by the reduction in the axial dimension of the central portion 4I of the hub 4 is reduced. Furthermore, the shaft 16 can be configured to be long, which is preferable in that it can prevent a decrease in bearing rigidity.

  Further, there is a problem that the axial dimension of the spiral portion cannot be sufficiently obtained with respect to the screw hole 4K provided in the hub 4. Corresponding to this problem, the screw hole 4K is formed to penetrate in the axial direction. Further, the cover member 31 is provided on a surface facing the coil 12 of the hub in which the screw hole 4K is formed. As a result, the problem that the axial dimension of the spiral portion of the screw hole 4K cannot be sufficiently reduced is reduced. Various materials can be applied to the cover member 31. For example, a PET film may be attached to the surface of the base member 3 facing the coil 12 with a double-sided tape. This method is preferable in that it can be easily operated and can also serve as an insulating process for the coil 12.

  Next, in the disk drive device 200 of the comparative technique of FIG. 4, the cylindrical portion 76 and the bottom portion 78 of the housing are fixed by bonding different members. However, when the disk drive device 200 is thinned, the bonded portion is also thinned. When the bonded portion becomes thin, the bonding strength decreases, and the bonding may be peeled off by an impact.

  Returning to FIG. In response to this problem, in the disk drive device 100 of the embodiment, the housing 13 has a bottomed cup shape in which the cylindrical portion and the bottom portion are integrally formed. As a result, even when the disk drive device 100 is thinned, the problem that the cylindrical portion and the bottom portion of the housing 13 are peeled off is reduced.

  Next, in the disk drive device 200 of the comparative technique of FIG. 4, the annular member 80 is fixed to the inner periphery of the annular protrusion of the hub 56 by adhesion. The donut-shaped annular member 80 has an axial dimension of 1.2 mm or more in order to ensure the bonding strength with the hub 56. However, when the disk drive device 200 is thinned, the axial dimension of the central portion of the hub 56 is thinned by the annular member 80. If the axial dimension of the central portion of the hub 56 is reduced, the resonance frequency of the disk drive device 200 is lowered, and a large vibration may be generated by resonating with fluctuations in the drive torque.

  Returning to FIG. In response to this problem, the bearing unit 5 according to the embodiment includes a hanging portion 20 that rotates integrally with the hub 4, and a protruding member that is non-rotatably disposed at a position facing the hanging portion 20 in the axial direction. 19 and. The hanging part 20 cooperates with the projecting member 19 to restrict the axial movement of the hub 4, and the axial width of the hanging part 20 facing the projecting member 19 may be 0.6 mm or less. Good. That is, the thickness of the disk part 20A of the hanging part 20 is set to 0.6 mm or less. As a result, when the disk drive device 100 is thinned, the axial dimension of the central portion 4I of the hub 4 can be secured. Furthermore, when the dimension of the hanging part 20 is 0.4 mm or less, it is preferable in that the axial dimension of the central part 4I of the hub 4 can be further increased.

  Moreover, when the axial direction dimension of the annular member 80 of FIG. 4 is made thin, the joint strength of the annular member 80 with the hub 56 decreases, and there is a problem that the joint is peeled off by an impact. Corresponding to this problem, the hanging part 20 is integrally formed with a disk part 20A facing the projecting member 19 in the axial direction and a cylindrical part 20B connected to the outer edge part of the disk part 20A. With this configuration, it is possible to sufficiently secure the axial dimension for joining to the annular protrusion 4E of the hub 4. As a result, the problem that the joint between the hanging part 20 and the hub 4 is peeled off is reduced. For example, the axial dimension of the cylindrical portion 20B is set to 2.0 mm or more to ensure a sufficient bonding strength with the hub 4. In addition, the axial dimension of the disk portion 20A is set to 0.4 mm or less, so that the axial dimension of the central portion 4I of the hub 4 can be made thick.

  There is a problem that much labor is required for processing the drooping portion 20. In response to this problem, the drooping portion 20 may be formed by pressing a metal material. As a result, it is possible to reduce the problem that it takes time to process the hanging part 20.

  A thrust dynamic pressure groove 23 may be formed on at least one surface of the disk portion 20A of the hanging portion 20. Specifically, the thrust dynamic pressure groove 23 is formed on at least one of the surface of the disk portion 20A facing the upper end surface of the opening of the housing 13 and the surface of the disk portion 20A facing the protruding member 19. As a result, the processing of the thrust dynamic pressure groove 23 is facilitated.

  Next, as the disk drive device 100 is made thinner, the stator core 11 is made thinner. When the stator core 11 is thinned, the stator core 11 may be inclined and attached even if the annular portion is fitted to the base member 3. In response to this problem, the stator core support member 32 is disposed between the salient poles of the stator core 11 and the base member 3. The stator core support member 32 protrudes in an annular shape from the base member 3 toward the salient pole of the stator core 11 on which the coil 12 is not provided. As a result, the stator core 11 is supported on the inner periphery and the outer periphery, and the problem that the stator core 11 is inclined due to the reduction in thickness is reduced.

  The stator core support member 32 is formed integrally with the base member 3. This is preferable because it does not require assembling work. The stator core support member 32 may be disposed as a separate member from the base member 3. It is preferable in that it can be formed of various materials such as metal materials and plastic materials.

  The portion of the hub 4 that covers the outer periphery of the magnet 21 functions as a so-called back yoke. As the back yoke becomes thinner, the magnetic resistance increases. As the magnetic resistance increases, the magnetic flux generated by the magnet 21 decreases. When the magnetic flux is reduced, there is a problem in that the torque is reduced and the rotation becomes unstable. In response to this problem, the hub 4 has an annular extending portion 4C extending outward, and the diameter of the outer peripheral end of the annular extending portion 4C is 4 mm or more larger than the diameter of the inner cylindrical portion 4D of the hub 4. To do. As a result, a sufficient thickness of the back yoke can be ensured, and problems due to torque reduction are reduced.

  If a strong magnet material is used to improve torque, the magnetic flux inside the back yoke is saturated and the leakage magnetic flux may increase. When the leakage flux increases, a noise signal is generated in the magnetic head that reads data. If this noise signal is large, normal magnetic data read and write operations may be disturbed. In response to this problem, the saturation magnetic flux density of the annular extending portion 4C functioning as a back yoke is set to 1 T (Tesla) or more. With this configuration, a sufficient saturation magnetic flux density can be secured in the back yoke, and the problem of increased leakage magnetic flux can be reduced. When the saturation magnetic flux density of the hub 4 is 1.2 T or more, a stronger magnet material can be used.

  Furthermore, there is a problem of improving torque and stabilizing rotation. Corresponding to this problem, the gap between the salient pole tip and the magnet 21 is set to 0.4 mm or less. As a result, the air gap of the magnetic circuit is reduced, the amount of magnetic flux of the magnet 21 is increased, and the torque is improved. The gap between the salient pole and the magnet 21 is preferably 0.4 mm or less from the viewpoint of securing the effect of improving the torque, and 0.2 mm or more is preferable in order to prevent the salient pole and the magnet 21 from contacting each other.

  Further, the maximum energy product of the magnet 21 according to the embodiment may be 10 MGOe (Mega Gauss Oersted) or more. Thereby, the magnetic flux amount of the magnet 21 is increased and the torque is improved. The maximum energy product of the magnet 21 is preferably 10 MGOe or more from the viewpoint of securing the effect of improving torque, and is preferably 16 MGOe or less from the viewpoint of easy magnetization. In addition, by using the magnet 21 having the maximum energy product and the back yoke having a saturation magnetic flux density of 1T or more in combination, the magnetic flux leaking from the back yoke can be suppressed even in the thin disk drive device 100.

  The disk drive device 100 mounted on a portable device has problems of further reduction in thickness and weight. Corresponding to this problem, the inner diameter of the recording disk 1 is set to 20 mm, and the axial thickness of the disk drive device is set to 7.5 mm or less. As a result, the portable device can be configured to be thin and lightweight. It can also contribute to resource saving.

  As described above, in the disk drive device 100 according to the embodiment, the rotation of the recording disk 1 can be stabilized while further reducing the shape so as to be suitable for a portable device or the like.

  The present invention is not limited to the above-described embodiment, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each figure is for explaining an example, and any configuration that can achieve the same function can be changed as appropriate, and the same effect can be obtained.

DESCRIPTION OF SYMBOLS 1 Recording disc, 2 Top cover, 3 Base member, 3A Bearing hole, 3B Wire hole, 3C Lower surface, 3D Groove part, 4 Hub, 4A Upper end surface, 4B Outer cylinder part, 4C Annular extension part, 4D Inner cylinder part, 4E Annular projection, 4F lower end surface, 4I center, 4J recess, 4K screw hole, 4M shaft hole, 5 bearing unit, 6 spindle drive unit, 7 fixed body part, 8 rotating body part, 9 screw, 10 chassis, 11 stator core , 12 coil, 13 housing, 14 sleeve, 14A opening end face, 15 circumferential ring wall, 15A annular part, 15B rectangular part, 15C screw hole, 16 shaft, 17 head drive unit, 19 overhang member, 20 hanging part, 20A Disc part, 20B cylindrical part, 21 mug , 22 radial dynamic pressure groove, 23 thrust dynamic pressure groove, 24 capillary seal part, 25 wire, 26 wiring member, 26A connection part, 27, 28 film, 29 clamper, 30 screw, 31 cover member, 32 stator core support member 40 first pressing mold, 42 second pressing mold, 50 stator core, 52 spindle drive unit, 54 magnet, 56 hub, 58 back yoke part, 62 coil, 70 clamper, 72 screw, 74 shaft, 80 annular member, 100, 200 disk drive.

Claims (20)

A base member;
A hub on which a recording disk is placed;
A bearing unit disposed on the base member and rotatably supporting the hub;
A spindle drive unit that rotationally drives the hub, and
The spindle drive unit is
A stator core having salient poles;
A coil wound around the salient pole;
A magnet having a plurality of magnetic poles in the circumferential direction facing the salient poles,
The hub is formed of a magnetic material, and has an outer cylinder part that engages with an inner periphery of the recording disk, and an inner cylinder part to which an outer periphery of the magnet is fixed,
2. The disk drive device according to claim 1, wherein the number of magnetic poles is an even number within a range of 10 to 16, and the number of salient poles is a multiple of 3 within a range of 12 to 24.   2. The disk drive device according to claim 1, wherein the number of magnetic poles is 10 and the number of salient poles is 15.   2. The disk drive device according to claim 1, wherein the number of magnetic poles is 12, and the number of salient poles is 18.   2. The disk drive device according to claim 1, wherein the number of magnetic poles is 14, and the number of salient poles is 21.   2. The disk drive device according to claim 1, wherein the number of magnetic poles is 16, and the number of salient poles is 24.   2. The disk drive device according to claim 1, wherein the number of the magnetic poles is 16, and the number of the salient poles is 12.   The disk drive device according to claim 1, wherein a diameter of the inner cylinder part is larger than a diameter of the outer cylinder part.   The diameter of the outer cylinder part is 20 mm, and the axial dimension of the surface facing the hub and the surface facing the base member of the coil is 3 mm or less. The disk drive described.   9. The disk drive device according to claim 1, wherein a surface of the coil facing the hub and a surface facing the base member are leveled.   The disk drive device according to claim 1, wherein a surface of the hub facing the coil is insulated.   The disk drive device according to claim 1, wherein a surface of the base member facing the coil is insulated.   The disk drive device according to claim 1, wherein an axial dimension of the hub facing the coil is larger than an axial dimension of the base member facing the coil. The hub is
A recess on the surface of the hub on which the recording disk is placed;
The disk drive device according to claim 1, wherein a clamper locking portion that locks a clamper that fixes the recording disk to the hub is formed in the recess.   13. The disk drive device according to claim 12, wherein the clamper locking portions are provided at 2 to 5 locations at circumferentially equidistant positions avoiding the bearing unit in the radial direction. The clamper locking portion is formed to be a hole penetrating in the axial direction,
15. The disk drive device according to claim 13 or 14, wherein a cover member is provided on a surface of the hub on which the clamper locking portion is formed facing the coil.   16. The disk drive device according to claim 1, wherein a gap where the salient pole and the magnet face each other is set to 0.4 mm or less.   16. The disk drive device according to claim 1, wherein a diameter of a circumscribed circle of the salient pole is larger than a diameter of the outer cylinder portion.   The diameter of the outer cylinder portion is 20 mm, and the axial dimension from the end of the hub opposite to the base to the end of the base opposite to the hub is 6 mm or less. The disk drive device according to any one of 17.   19. The disk drive device according to claim 1, wherein an inner diameter of the recording disk is 20 mm, and a thickness of the disk drive device is 7.5 mm or less.   The method for manufacturing a disk drive device according to any one of claims 1 to 19, further comprising a film sticking step of attaching a film with an adhesive member interposed on a surface of the hub facing the coil.

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